Keyboard Problem, Extra Characters

What Operating System are you running - if Windows what version XP, vista, 7? When is it shutting down, after you get into Windows (or other OS) or when trying to boot up? Are there any error messages? New machine or old machine - if old has anything changed? How long does the system stay working before it shutsdown? Is it getting too hot, fans blocked etc?
Lets start by working out if it is the hardware (Dell and devices connected) or the software (Windows etc) It is difficult to know without more details of the problem but here are my best suggestions
Try safe mode - running windows try in safe mode (F8 when starting windows), check error logs
Test the hardware - I would start by disconnecting all external devices, USB disk and other devices. If possible also remove any extra boards you have added to the machine. Even the mouse, USB sticks, anything plugged in (but leave the keyboard). Try this, do you get the same problem.
Test the OS - If you have a live CD such as Ubuntu (can be downloaded from here: http://www.ubuntu.com/desktop/get-ubuntu/download ) then try booting the system from this and see if you still get a problem
Can you run a virus checker on it, how long does the machine stay running. You can try downloading from here from another machine - http://www.avg.com/us-en/avg-rescue-cd-download and making a CD, run the rescue anti virus.

Alt+0241

On Windows, the Alt key functions as a modifier like the Shift key. To make special characters, hold down the Alt key and type in the numbers from the numeric keypad. Note that on the some small keyboards (e.g. laptop keybaords) the “numeric keypad” is found by pressing the NumLock key and then looking for the keys on your keyboard that double as numeric keypad keys when in NumLock mode.

The keyboard fix is easy, replace the keyboard, same for the battery.
Manual is here
http://support.dell.com/support/edocs/systems/latc610/sm_en/index.htm
you can buy a keyboard here
http://cgi.ebay.com/New-Keyboard-Dell-Latitude-C510-C540-C600-C610-C640-/170342472542?cmd=ViewItem&pt=PCA_Mice_Trackballs&hash=item27a933db5e#ht_2468wt_1202
battery here
http://cgi.ebay.com/66WHR-Battery-Dell-Latitude-C500-510-C540-C600-C610-/280475115213?cmd=ViewItem&pt=Laptop_Batteries&hash=item414d9e9ecd#ht_2340wt_1734
S-Video on that model pretty much requires a direct S-Video to TV connection, then enable the TV in the Display properties. If you are trying to use an adapter, it will not work

you have a bad keyboard. think about replacing instead of repairing.

If it runs Windows 2000 well, it should handle XP just fine.

If you put a BootCD in the CD drive then turn the system on you should be able to format the HDD from the CD. Also, your new operating system disk should allow you to reformat the HDD. Just put the CD in and start the computer up again. Watch for a message to press the spacebar or any other key to boot from the CD.

Control panel-
regional and language options-
languages-
details-
now set the country you are in

I'm a little late to the game, but...
I share James's frustration. Seems like a dumb thing for Dell to economize on. Here's my workaround, for what it's worth.

1. Open the Windows on-screen keyboard (osk.exe). And, for later ease of use, pin it to your taskbar. (Detailed instructions: click on the Windows start button, type osk.exe in the search box, right-click on the program, select Pin to Taskbar.)
2. On the virtual keyboard, open Options and select "Turn on the numeric keypad." After saving the setting, press the NumLock button.
   
3. Here's the tricky bit: press and hold Alt on your physical keyboard, and then press and hold Fn, again on your physical keyboard. You're holding them both down, right? Keep doing it. Now enter your four-digit code on the virtual (on-screen) keyboard. Release the physical keys. You should have your special character.

Hope it works for you.

I was using microsofts intelitype pro software

@:http://www.download.com/Microsoft-IntelliType-Pro-2000-XP-/3000-2110_4-10226336.html

for my Dell multimedia keyboard..I had to run the program at every reboot. but it worked great for 2 years..But recently I had to reinstall windows and now I cant get that or any other program to work for my keyboard volume.

Well once you did a clean install over all of Dell drivers etc etc. You wiped out the restore artion that was on the computer. You have to go to Dells website and under the support tab look for the Nic card that you have inside the computer.